<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    body{
      background: blue;
    }
    svg{
      stroke-linecap: round; /*线的两端圆角*/
      stroke-linejoin: round;/*线折点部分圆角*/
    }
    path{
      fill:none;
      stroke:#fff;
      stroke-width:5;
      stroke-dasharray: 150 350;
      transition: all 0.3s ease-in-out ;
    }
    .current #top,.current #bot{
      stroke-dashoffset: -330;
    }
  </style>
</head>
<body>
  <svg width=300 height=300 id='arrow'>
    <g>
      <g>
        <!-- // 上边的横线 -->
        <path id='top' d="M75,90 L225,90 C270,50 180,30 75,150"></path>
      </g>
      <g>
        <!-- // 中间的横线 -->
        <path  d="M75,150 L225,150"></path>
      </g>
      <!-- <g transform="translate(0,60)"> -->
        <!-- // 中间的横线 -->
        <path transform="translate(0,60)" id='bot' d="M75,150 L225,150 C270,190 180,210 75,90"></path>
      <!-- </g> -->
    </g>
  </svg>
  <script>
    let arrow = document.getElementById('arrow');
    arrow.onclick = function(){
      this.classList.toggle('current')
    }
  </script>
</body>
</html>